>> reporter: when the clock struck midnight in seattle thursday, 100 or so pot lovers gathered beneath the space needle to light up. recreational use of marijuana is now legal in washington state, after voters approved the measure on november 6th. >> washington voters were very ready for a new approach to marijuana. >> reporter: a new approach that led to adults over 21, possess up to an ounce of pot and use it, but only in private. which means the very public midnight celebration was in fact illegal. the new law, though, conflicts with the federal ban on marijuana. doesn't tell police how to go about enforcing it. and lacks specifics on how to license growers and retailers to produce and sell it. >> clearly there's this major problem, you know, that has to be worked out through committee quickly. >> reporter: but state officials say they're plowing forward because prohibition got expensive. the state spent $100 million a year prosecuting pot users. >> washington state is a wash as most states are in marijuana. which is one points prohibition has failed in its purpose. >> reporter: whi